Sarawak Forestry Corporation

Kuching, Malaysia

Sarawak Forestry Corporation

Kuching, Malaysia
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Peay K.G.,University of California at Berkeley | Kennedy P.G.,Lewis And Clark College | Davies S.J.,Harvard University | Tan S.,Sarawak Forestry Corporation | And 2 more authors.
New Phytologist | Year: 2010

Relatively little is known about diversity or structure of tropical ectomycorrhizal communities or their roles in tropical ecosystem dynamics. In this study, we present one of the largest molecular studies to date of an ectomycorrhizal community in lowland dipterocarp rainforest. We sampled roots from two 0.4 ha sites located across an ecotone within a 52 ha forest dynamics plot. Our plots contained > 500 tree species and > 40 species of ectomycorrhizal host plants. Fungi were identified by sequencing ribosomal RNA genes. The community was dominated by the Russulales (30 species), Boletales (17), Agaricales (18), Thelephorales (13) and Cantharellales (12). Total species richness appeared comparable to molecular studies of temperate forests. Community structure changed across the ecotone, although it was not possible to separate the role of environmental factors vs host plant preferences. Phylogenetic analyses were consistent with a model of community assembly where habitat associations are influenced by evolutionary conservatism of functional traits within ectomycorrhizal lineages. Because changes in the ectomycorrhizal fungal community parallel those of the tree community at this site, this study demonstrates the potential link between the distribution of tropical tree diversity and the distribution of tropical ectomycorrhizal diversity in relation to local-scale edaphic variation. © 2009 New Phytologist.


Katabuchi M.,Tohoku University | Kurokawa H.,Tohoku University | Davies S.J.,Harvard University | Tan S.,Sarawak Forestry Corporation | Nakashizuka T.,Tohoku University
Journal of Ecology | Year: 2012

Habitat filtering and limiting similarity have been proposed as two opposing forces structuring community memberships. Community assembly theory proposes habitat filtering as a mechanism restricting community membership according to the ecological strategies of species in a given environment. Limiting similarity posits that some species exclude others that are ecologically similar. We quantified nine ecophysiological and life-history traits for 80 dipterocarp species in the 52-ha Lambir Forest Dynamics Plot (FDP; Lambir Hills National Park, Sarawak, Malaysia). We studied forests on four soil types differing in fertility and moisture, focusing on soil resource availabilities as environmental determinants of habitat filtering processes. We used a null-model approach to detect the strengths of habitat filtering and limiting similarity. We quantified the relative contributions of soil resources (nutrients and water) to habitat filtering by comparing the strength of habitat filtering processes (i.e. effect sizes) at the overall plot scale and at the individual soil-type scale. We also compared the strengths of assembly processes among soil types. Compared to a null model at microscale (20×20m), trait range and variance were reduced for seven of nine functional traits, suggesting the importance of habitat filtering in the dipterocarp community. We also found a broader distribution of five traits, and more even spacing for seven traits (20×20m), which is consistent with the concept of limiting similarity. Randomizations that swapped species occurrences within soil types (i.e. null models removing soil effects in assembly processes) were much closer to observed values, and there were no phylogenetic constraints on habitat association. Hence, soil resource availability acted as a habitat filtering mechanism in the FDP; relative contributions to habitat filtering ranged from 35% for seed mass to 77% for relative growth rate. Furthermore, soil types apparently affected the strengths of habitat filtering and limiting similarity. Synthesis.We demonstrate that soil resource availability is a crucial determinant of habitat filtering in this species-rich tropical rain forest; the strengths of assembly processes differed among soil types. Variation in soil resource availability can shape the distribution of traits through community assembly processes, promoting trait diversification and species coexistence. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.


Itoh A.,Osaka City University | Nanami S.,Osaka City University | Harata T.,Osaka City University | Ohkubo T.,Utsunomiya University | And 5 more authors.
Biotropica | Year: 2012

The effects of El Niño-induced droughts on dipterocarp forests must be quantified to evaluate the implications of future global climatic changes for the tropical forests of Southeast Asia. We studied the mortality of trees ≥ 1 cm in diameter in a lowland dipterocarp forest in Borneo before, during, and after the 1997/1998 El Niño drought. The annual mortality rates were 1.30, 1.75, and 1.66 percent/yr for the pre-drought, drought, and post-drought periods, respectively. The effect of drought was tree size-dependent being greater for larger trees. Modified logistic regression analysis revealed a significant interaction effect between species' habitat association and edaphic condition on mortality rates in all periods. For species associated with wet habitat, drought effect was greater in dry conditions than in wet conditions, in both the drought and post-drought periods. The mortality rates of dry-habitat species were less affected by the drought both in dry and wet conditions. A similar pattern was also found in common Dipterocarpaceae species; mortality rates increased more in species associated with wet-habitat in the drought and post-drought periods. Species and families with higher mortality in the pre-drought period tended to experience greater mortality increases during the drought and post-drought periods. These results suggest that changes in drought regimes alter the species composition and spatial distribution of dipterocarp forests. © 2012 The Author(s) Journal compilation © 2012 by The Association for Tropical Biology and Conservation.


Harata T.,Osaka City University | Nanami S.,Osaka City University | Yamakura T.,Osaka City University | Matsuyama S.,Osaka City University | And 4 more authors.
Biotropica | Year: 2012

Fine-scale spatial genetic structure is increasingly recognized as an important factor in the studies of tropical forest trees as it influences genetic diversity of local populations. The biologic mechanisms that generate fine-scale spatial genetic structure are not fully understood. We studied fine-scale spatial genetic structure in ten coexisting dipterocarp tree species in a Bornean rain forest using microsatellite markers. Six of the ten species showed statistically significant fine-scale spatial genetic structure. Fine-scale spatial genetic structure was stronger at smaller spatial scales (≤ 100 m) than at larger spatial scales (> 100 m) for each species. Multiple regression analysis suggested that seed dispersal distance was important at the smaller spatial scale. At the larger scale (> 100 m) and over the entire sample range (0-1000 m), pollinators and spatial distribution of adult trees were more important determinants of fine-scale spatial genetic structure. Fine-scale spatial genetic structure was stronger in species pollinated by less mobile small beetles than in species pollinated by the more mobile giant honeybee (Apis dorsata). It was also stronger in species where adult tree distributions were more clumped. The hypothesized mechanisms underlying the negative correlation between clump size and fine-scale spatial genetic structure were a large overlap among seed shadows and genetic drift within clumped species. © 2011 The Author(s) Journal compilation © 2011 by The Association for Tropical Biology and Conservation.


Russo S.E.,University of Nebraska - Lincoln | Russo S.E.,Harvard University | Cannon W.L.,University of Nebraska - Lincoln | Elowsky C.,University of Nebraska - Lincoln | And 3 more authors.
American Journal of Botany | Year: 2010

Premise of the study: Quantifying variation in functional traits associated with shifts in the species composition of plant communities along resource gradients helps identify environmental attributes important for community assembly. Stomates regulate the balance between carbon assimilation and water status in plants. If environmental attributes affecting photosynthetic water-use efficiency govern species distribution along an edaphic gradient, then adaptive variation in stomatal traits of plant species specializing on different soils should reflect belowground resource availability. Methods: We tested this hypothesis by quantifying stomatal trait variation in understory saplings of 28 Bornean tree species in relation to gas exchange and water-use efficiency (WUE). Key results: Comparisons between congeneric specialists of the more fertile, moister clay and the less fertile, well-drained sandy loam revealed little evidence of similar shifts in stomatal traits across genera, nor was stomatal pore index correlated with gmax, Amax, or WUE (Amax/gmax or Δ13 C), suggesting that stomates may be overbuilt in these shaded juveniles. Amax was higher on sandy loam, likely due to higher understory irradiance there, but there were no other significant differences in gas exchange or WUE. Conclusions: Despite substantial diversity in stomatal anatomy, there were few strong relationships between stomatal, photosynthetic, and WUE traits in relation to soil resources. Routine differences in water availability therefore may not exert a dominant control on the distributions of these Bornean tree species. Furthermore, the clades represented by these 12 genera may possess alternative functional designs enabling photosynthetic WUE that is sufficient to these humid, understory environments, due to whole plant-functional integration of stomatal traits with other, unmeasured traits influencing gas exchange. © 2010 Botanical Society of America.


Heineman K.D.,University of Nebraska - Lincoln | Jensen E.,University of Nebraska - Lincoln | Shapland A.,University of Nebraska - Lincoln | Bogenrief B.,University of Nebraska - Lincoln | And 3 more authors.
Forest Ecology and Management | Year: 2011

Tree height and crown allometries reflect adaptations for resource acquisition and structural stability, as well as plastic responses to a heterogeneous environment. While both light and soil resources limit growth and influence competitive responses in tropical forests, the effects of belowground resources on allometries are less understood, especially within the understory. To characterize outcomes of tree competition along an edaphic resource gradient, we quantified variation in height and crown allometries of six Bornean tree species from contrasting regeneration niches (light-demanding vs. shade-tolerant) on two soil habitats (clay-fine loam and sandy loam) within a 52-ha forest dynamics plot. Using empirically-fit allometric parameters and diameter growth rates from plot census data, we modeled tree height and crown area growth over the projected life span of each species. Based on resource competition theory, we hypothesized that tree species specializing on and populations of generalist species growing on the relatively moister, more fertile clay-fine loam soil habitat would have faster height and crown growth rates, compared to those on the sandy loam habitat, regardless of regeneration niche. Among soil specialists and within generalists of both genera, trees growing on clay-fine loam had taller stems and larger crowns at a given age and faster height and crown area growth rates at most sizes than trees on sandy loam. Differences in height and crown growth were driven by the faster diameter growth rates of trees on clay-fine loam, not by differences in height- and crown-diameter allometries, as trees on sandy loam were significantly taller at a given diameter, and differences in crown allometry were not consistent across soil habitats. Characterizing the height and crown growth responses of trees along resource gradients provides insight into the mechanisms that maintain diversity in tropical forests. Our results point to the importance of adaptive and plastic responses to both above and belowground resource availability in determining the allometric growth of trees and suggest that this diversity of responses may contribute tree species coexistence through competition-based trade-off mechanisms and variation in growth among individuals. Additionally, as the importance estimating natural carbon sequestration increases with the escalating effects of anthropogenic climate change, differences in tree growth and architecture across soil habitats also have implications for the approximation of forest carbon storage on heterogeneous tropical soils. © 2011 Elsevier B.V.


Miyashita N.T.,Kyoto University | Iwanaga H.,Kyoto University | Charles S.,Sarawak Forestry Corporation | Diway B.,Sarawak Forestry Corporation | And 2 more authors.
Genes and Genetic Systems | Year: 2013

Bacterial community structure was investigated in five tropical rainforests in Sarawak, Malaysia and one temperate forest in Kyoto, Japan. A hierarchical sampling approach was employed, in which soil samples were collected from five sampling-sites within each forest. Pyrosequencing was performed to analyze a total of 493,790 16S rRNA amplicons. Despite differences in aboveground conditions, the composition of bacterial groups was similar across all sampling-sites and forests, with Acidobacteria, Proteobacteria, Verrucomicrobia, Planctomycetes and Bacteroidetes accounting for 90% of all Phyla detected. At higher taxonomic levels, the same taxa were predominant, although there was significant heterogeneity in relative abundance of specific taxa across sampling-sites within one forest or across different forests. In all forests, the level of bacterial diversity, estimated using the Chao1 index, was on the order of 1,000, suggesting that tropical rainforests did not necessarily have a large soil bacterial diversity. The average number of reads per species (OTUs) per sampling-site was 8.0, and more than 40-50% of species were singletons, indicating that most bacterial species occurred infrequently and that few bacterial species achieved high predominance. Approximately 30% of species were specific to one sampling-site within a forest, and 40-60% of species were uniquely detected in one of the six forests studied here. Only 0.2% of species were detected in all forests, while on average 32.1% of species were detected in all sampling-sites within a forest. The results suggested that bacterial communities adapted to specific micro- and macro-environments, but macro-environmental diversity made a larger contribution to total bacterial diversity in forest soil.


Sang J.,Sarawak Forestry Corporation | Kiew R.,Malaysian Forest Research Institute
Phytotaxa | Year: 2016

Nine Begonia species are recorded from the Batang Ai National Park and the forest area adjacent to the Park. Of these, six species are described here as new (Begonia acidulenta, Begonia bayae, Begonia compacta, Begonia edgariana, Begonia jenginensis and Begonia tebiang). All species belong to section Petermannia. A key to the new species and three species previously described by Lin et al. (2014) is provided. Following the guidelines for the IUCN Categories and Criteria, the proposed conservation status of the seven new species known from the national park is assessed as “Least Concern”. © 2016 Magnolia Press.


Sang J.,Sarawak Forestry Corporation | Kiew R.,Malaysian Forest Research Institute | Yiing L.C.,Sarawak Forestry Corporation
Phytotaxa | Year: 2016

Six new species of Begonia, Begonia armykapii S.Julia & C.Y.Ling, Begonia baikoides S.Julia & C.Y.Ling, Begonia papulifolia S.Julia & C.Y.Ling, Begonia rubrobracteolata S.Julia & C.Y.Ling, Begonia tinjanii S.Julia and Begonia triangularis Kiew & C.Y.Ling, are described from the forest areas in central part of Sarawak. All species belong to the sect. Petermannia. © 2016 Magnolia Press.


Gan K.S.,Malaysian Forest Research Institute | Zairul A.R.,Malaysian Forest Research Institute | Tan J.L.,Sarawak Forestry Corporation
Journal of Tropical Forest Science | Year: 2015

Timber drying is an important manufacturing process for efficient timber utilisation. Time and cost can be substantial in the development of appropriate drying schedule for unfamiliar timber with unknown drying characteristics, for example refractory timbers. These include heavy hardwood species and plantation timbers that are prone to drying defects under inappropriate drying schedule. As such, a quick drying assessment protocol will be helpful to reduce the cost and time of developing suitable drying schedule. This study demonstrated the use of the protocol for drying rate test to evaluate the effectiveness of pretreatment processes on Acacia mangium timber. The conventional steam-heated kiln drying of this timber is known to produce high occurrence of wet pockets. Pretreatments processes tested included air drying, hot water bath and microwave treatments. Results from the drying trials suggested that hot water bath and microwave pretreatments with appropriate settings after air drying could expedite drying process and alleviate the occurrence of wet pockets in A. mangium. © Forest Research Institute Malaysia

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